SGP/SIRS/C1 - NIP failure

The short_direct_normal (NIP instrument) cable failed during this time period.	Data are 
not recoverable.

Users can derive an estimate of direct normal values using the following formula:
short_direct_normal = (down_short_hemisp - down_short_diffuse_hemisp)/cos(zenith angle)

• inst_direct_normal

• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• short_direct_normal_std
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)

SGP/SIRS/C1 - Reprocess: Incorrect downwelling longwave calibration coefficient

Calibration coefficient for downwelling longwave was incorrect for the specified period.

To correct the one minute data b1 datastream follow the procedure below:
1) Obtain the following variables from the 20s datastream for each one minute of the 
affected time range:
  inst_down_long_shaded_dome_resist (Rd)
  inst_down_long_shaded_case_resist (Rc)
  inst_down_long_hemisp_shaded_tp (tpDIR_mV)
                                         
2) using the 20s tp voltage in mV convert to uV.
  tpDIR[uV] = inst_down_long_hemisp_shaded_tp[mV]*1000[uV/mV]

3) For each 20s data entry convert Rd and Rc to temperature
  Td =1/ (a0 + (a1*LN (Rd*1000) + (a2*LN (Rd*1000)^3)))
  Tc = 1/ (a0 + (a1*LN (Rc*1000) + (a2*LN (Rc*1000)^3)))
  where a0 = 0.0010295 
        a1 = 0.0002391
        a2 = 0.0000001568

4) Apply for each 20s data entry: (correct k1=0.2762)
  WinDIR(W/m2)= [0.2762*tpDIR] + Sigma*Tc^4 -4*Sigma*(Td^4 - Tc^4)
  where, Sigma = 5.6704E-8 (Stefan-Boltzman Const)
                                      
5) Generate new 1 minute average from the 3 20-second measurements

• inst_down_long_shaded_dome_resist
• inst_down_long_shaded_case_resist
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded_tp)

• Downwelling Longwave Hemispheric Irrad., Shaded Ventilated Pyrgeometer, Maxima(down_long_hemisp_shaded_max)
• down_long_hemisp_shaded_std
• Downwelling Longwave Hemispheric Irrad., Shaded Ventilated Pyrgeometer, Minima(down_long_hemisp_shaded_min)
• Downwelling Longwave Hemispheric Net Infrared(down_long_netir)
• inst_down_long_shaded_case_temp
• Downwelling Longwave Hemispheric Irradiance, Shaded Ventilated Pyrgeometer(down_long_hemisp_shaded)
• inst_down_long_shaded_dome_temp